Internal-combustion engine



July 15, 1924. i,501,531

' W. B. EARNSHAW INTERNAL COMBUSTION ENGINE Filed Oct. 15. 1920 Z SheetS-Sheet l 'OGQ' W. B. EARNSHAW INTERNAL COMBUSTION ENGINE July 15 1924. 1,501,531

Filed Oct. 15 l92 O 2 Sheets-Sheet 2 [173m ZHUE'HTUT" f fiiM WM 6 6 Patented July 15, 1924.

UNITED STATES PATENT OFFICE.

WILLIAM B. EARNSKAW, OF DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS IRE- SEARCH CORPORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE.

INTERNAL-COMBUSTION ENGINE.

Application filed October 15, 1920. Serial No. 417,218.

T 0 all whom it may concern:

Be it known that I, WILLIAM B. EARN- BHAW, a citizen of the United States of America, residing at Dayton, county of Montgomery, and State of Ohio, have invented certain new and useful Improvements in Internal-Combustion Engines, of which the following is a full, clear, and exact description.

The present invention relates to internalcombustion engines and more particularly to means for cooling spark plugs of such engines.

In the operation of internal-combustion engines it is frequently the case that the electrodes of the spark plugs become very highly heated and particularly is this true in the case of air cooled engines. Such heating can and does take place with water cooled engines but perhaps not so frequently.

The result of such high heating of the electrodes of the spark plug is quite noticeable in falling off of the power in the engine and in the life of the plug. The falling off of the power of such engines is due in a great measure to preignition of the fuel mixture.

Among other eflects of the undue heating of the spark plug is the warping of the electrodes and the consequent increase or diminishing of the spark gap, giving either no spark at all in the one case or too Weak a spark in the other case.

It is the object of the present invention, therefore, to overcome these deleterious effects and to produce means which will function at all times to overcome this prematuring and tend to increase the life of the plug.

Further objects and advantages of the present invention will be apparent from the.

following description, reference being had to the accompanying drawing wherein a preferred embodiment of the'present 1nvention is clearly shown.

In the drawings:

Fig. 1 illustrates an air cooled internalcombustion engine cylinder with an ordinary type of spark plug and with the cooler in place.

Fig. 2 is a plan view of the cylinder shown in Fig. 1.

Fig. 3 is a view similar to Fig. 2 of the cooling device along.

Fig. 4 is an elevation of the cooling device looked at from the direction indicated by the arrow in Fig. 3.

Fig. 5 is an elevation of a modification of the device.

Fig. 6 is an elevation partly in section of a second modification, and

Figs. 7 and 8 are respectively a plan and elevation of still another modification of the device.

As indicated in the drawings the'cooling device comprises in its preferred form, which has been chosen for the purpose of description, a metal plate 10 provided with a threaded passage 11 for receiving and holding the spark plug.

The plate 10 is also provided with the holes 12 whereby it may be attached to the cylinder head by means of screws 13 as indicated in Fig. 2.

The plate 10 is provided on one of its edges with a series of metal cooling fins or elements 14.

A modified form of the device is shown in Fig. 5. In this form instead of having the fins 14 attached to the edge of plate 10, this plate is bent at right angles as indicated at 10', and the fins are thus furnished with a greater area for attachment. In attaching the device to the cylinder, the plate 10, carrying the fins 14, is first secured or bolted to the cylinder head as indicated in Fig. 1 with a sheet of heat insulating material 20 between it and the metal of the cylinder head. The plate is so positioned as to have the fins or cooling elements projecting beyond the edge of the cylinder head into the stream of cooling air. After the plate has been secured into the cylinder as mentioned, the spark plug is secured into the hole or passage 11 in the ordinary manner of inserting spark plugs.

In the form of cooler shown in Fig. 6, instead of fastening the plate 10 to the cylinder as in Figs. 1 to 5, this plate is provided with a tapering passage 11 shaped to fit over a correspondingly tapered portion of the spark plug and is not attached directly to the cylinder. In this form a bushing 22 is threaded into the cylinder and is itself provided with threads for receiving the spark plug. Suitable insulating gaskets 21 are placed under the flange of the bushin and on top thereof, whereupon the spar plug is screwed into the bushing through the tapered passage-way 11 in plate 10. These tapered surfaces form a slidin fit and upon screwing the plug in tightly, orm a very good heat conducting contact while the two threaded contacts, between the plug and the bushing and between the bushing and the cylinder, offer more resistance to the heat.

In Figs. 7 and 8 the plate 10 is replaced by the clamping ring or element 30, which surrounds a cylindrical portion of the spark plug and is so placed as not to contact with the cylinder.

The operation of the device, as will be readily seen, is as follows:

The plate 10 or clamp 30 being heat insulated from the cylinder and carrying. the spark plug will abstract heat from the spark plug and conduct it to the cooling fins, which will in turn allow the heat to be dissipated to the cooling air.

In the preferred form of the construction, plate 10 (or clamp 30) and the fins 14 are both made of copper, because this metal has a very much higher heat conductivity than the usual ferrous metal cylinder, and has been found to give very excellent results. The plate 10 should be of sufiicient thickness to furnish a safe attachment for the spark plug, and being of sutficient thickness for this purpose will be of sutficient heat conductive capacity to abstract the heat absorbed by the spark plug. Further the thin sheet copper fins with large radiating sleeves serve to withdraw the heat from the -plate 10 and will readily give it up to the air or other cooling medium flowing over their surfaces. Although copper is the preferred metal for use in forming both parts of the device, it should be understood that the invention is not limited to the use of such metal but other metals e. g., aluminum, are contemplated, although they are not considered to be quite so good.

While the description has referred to the conducting element 10 as a plate it should be understood that a suitable ring or other form of conductor may be used, and in the claims, the plate and these other forms will be referred to as conductors or heat conducting elements.

lVhile the form of device herein shown and described, constitutes a preferred embodiment of the invention, it is to be understood that other forms might be adopt-- ed, all coming within the scope of the claims which follow.

What I claim is as follows:

1. The combination with an air cooled combustion engine cylinder of means for cooling the spark plug, the means comprising a copper plate attached to the cylinder but heat insulated therefrom, said plate being provided with means for attaching the spark plug and also with cooling fins disposed within the current of cooling air.

2. The combination with an internalcombustion engine cylinder of means for dissipating heat from a spark plug; the means comprising a heat conducting element heat insulated from the cylinder; means for fixing the spark plug in heat conducting relation to the element and in operative relation to the cylinder; and means attached to the element for conducting away and dissipating the heat withdrawn from the spark plug.

A spark plug cooler comprising a copper heat conductor provided at one portion with means for attachment in heat insulated relation to a cylinder of an internalcombustion engine and also provided with means for fixing thereto in heat conducting relation a spark plug, the conductor having a portion at an angle to the first mentioned portion and having cooling fins composed of thin copper sheets attached to the second mentioned portion.

at. A spark plug cooler comprising a copper heat conductor provided with means for attachment of said conductor to the cylinder of an internal-combustion engine and also provided with means for attaching thereto a spark plug, the conductor being bent substantially at right angles and having attached to the bent portion cooling fins composed of thin copper sheets.

5. In combination with an intei'nalcoin. bustion'engine cylinder provided with cooling means and also provided with a spark plug, means for independently cooling the spark plug and means for substantially heat insulating the latter cooling means from the cylinder.

6. In combination with an internal-combustion engine cylinder provided with cooling means and also provided with a spark plug, means for independently cooling the spark plug and means for substantially heat insulating the latter cooling means and spark plug from the cylinder.

7. In combination an air cooled engine cylinder provided with longitudinal cooling fins; a spark plug; and a cooler for the latter comprising a metal plate adapted for attachment to the cylinder and to the spark plu and which is provided with cooling surfaces adapted to project into the path of cooling passing over the longitudinal cooling fins.

In testimony whereof I hereto afiix my signature.

WILLIAM B. EARNSHAW.

ALVINA O. I/EHMAN. 

